#include <stdio.h>
#include "crc8.h"
unsigned char crc8_table[256] = {
	0x00,0x07,0x0e,0x09,0x1c,0x1b,0x12,0x15,0x38,0x3f,0x36,0x31,0x24,0x23,0x2a,0x2d,
	0x70,0x77,0x7e,0x79,0x6c,0x6b,0x62,0x65,0x48,0x4f,0x46,0x41,0x54,0x53,0x5a,0x5d,
	0xe0,0xe7,0xee,0xe9,0xfc,0xfb,0xf2,0xf5,0xd8,0xdf,0xd6,0xd1,0xc4,0xc3,0xca,0xcd,
	0x90,0x97,0x9e,0x99,0x8c,0x8b,0x82,0x85,0xa8,0xaf,0xa6,0xa1,0xb4,0xb3,0xba,0xbd,
	0xc7,0xc0,0xc9,0xce,0xdb,0xdc,0xd5,0xd2,0xff,0xf8,0xf1,0xf6,0xe3,0xe4,0xed,0xea,
	0xb7,0xb0,0xb9,0xbe,0xab,0xac,0xa5,0xa2,0x8f,0x88,0x81,0x86,0x93,0x94,0x9d,0x9a,
	0x27,0x20,0x29,0x2e,0x3b,0x3c,0x35,0x32,0x1f,0x18,0x11,0x16,0x03,0x04,0x0d,0x0a,
	0x57,0x50,0x59,0x5e,0x4b,0x4c,0x45,0x42,0x6f,0x68,0x61,0x66,0x73,0x74,0x7d,0x7a,
	0x89,0x8e,0x87,0x80,0x95,0x92,0x9b,0x9c,0xb1,0xb6,0xbf,0xb8,0xad,0xaa,0xa3,0xa4,
	0xf9,0xfe,0xf7,0xf0,0xe5,0xe2,0xeb,0xec,0xc1,0xc6,0xcf,0xc8,0xdd,0xda,0xd3,0xd4,
	0x69,0x6e,0x67,0x60,0x75,0x72,0x7b,0x7c,0x51,0x56,0x5f,0x58,0x4d,0x4a,0x43,0x44,
	0x19,0x1e,0x17,0x10,0x05,0x02,0x0b,0x0c,0x21,0x26,0x2f,0x28,0x3d,0x3a,0x33,0x34,
	0x4e,0x49,0x40,0x47,0x52,0x55,0x5c,0x5b,0x76,0x71,0x78,0x7f,0x6a,0x6d,0x64,0x63,
	0x3e,0x39,0x30,0x37,0x22,0x25,0x2c,0x2b,0x06,0x01,0x08,0x0f,0x1a,0x1d,0x14,0x13,
	0xae,0xa9,0xa0,0xa7,0xb2,0xb5,0xbc,0xbb,0x96,0x91,0x98,0x9f,0x8a,0x8d,0x84,0x83,
	0xde,0xd9,0xd0,0xd7,0xc2,0xc5,0xcc,0xcb,0xe6,0xe1,0xe8,0xef,0xfa,0xfd,0xf4,0xf3,
};

/* Create an 8-bit crc table from the polynomial x^8 + x^2 + x + 1  ~ 0x07 */
void init_crc8(void) // needn't
{
	int i;
	int j;
	unsigned char crc;

	for (i=0; i<256; i++) {
		crc = i;
		for (j=0; j<8; j++) {
			crc = (crc << 1) ^ ((crc & 0x80) ? 0x07 : 0);
		}
		crc8_table[i] = crc & 0xFF;
    }
}

uint8_t crc8(uint8_t crc, const char *s, int l) 
{
    int j = 0;
    uint8_t byte;

    for (j = 0; j < l; j++) {
        byte = s[j];
        crc = ((crc8_table[crc ^ byte]) & 0xFF);
    }
    return crc;

}
uint8_t crc8_file(char *filename, unsigned char *result)
{
    FILE *file;
    int len;
    unsigned char buffer[1024];
    unsigned char crc = 0x0;
 
    if ((file = fopen (filename, "rb")) == NULL) {
        return -1;
    } else {
        while ((len = fread (buffer, 1, 1024, file)) != 0) {
            crc = crc8(crc, buffer, len);
        }
        *result = crc;
        fclose (file);
        return 0;
    }
}

